Shell scripts are the recommended choice for ZEDLETs that mostly call
other utilities and do relatively little data manipulation.

Shell scripts MUST work on both bash and dash.

Shell scripts MUST run cleanly through ShellCheck:
  http://www.shellcheck.net/

General functions reside in "zed-functions.sh".  Use them where applicable.

Additional references that may be of use:

  Google Shell Style Guide
  https://github.com/google/styleguide/blob/gh-pages/shell.xml

  Dash as /bin/sh
  https://wiki.ubuntu.com/DashAsBinSh

  Common shell script mistakes
  http://www.pixelbeat.org/programming/shell_script_mistakes.html

  Filenames and Pathnames in Shell: How to do it Correctly
  http://www.dwheeler.com/essays/filenames-in-shell.html

  Autoconf: Portable Shell Programming
  https://www.gnu.org/software/autoconf/manual/autoconf.html#Portable-Shell

Please BE CONSISTENT with the existing style, check for errors,
minimize dependencies where possible, try to be portable,
and comment anything non-obvious.  Festina lente.